Francis celebrated a Mass in St. Peter's Basilica on Sunday dedicated to heightening awareness about poor people worldwide.

"We go our way in haste, without worrying that gaps are increasing, that the greed of a few is adding to the poverty of many others," Francis said in his homily, with poor people among the people accorded seats in the basilica for the Mass.

Keeping a tradition of his papacy, Francis invited indigent persons to dine with him at the Vatican after Mass.

Addressing the public in St. Peter's Square following the end of the service, Francis said such initiatives pay witness to "the attention that must never be lacking toward these brothers and sisters of ours".

He expressed dismay over the "indifference of society toward poor people".

Like the saint who inspired his choice of name, Francis of Assisi, the Pope has made paying attention to those living on society's margins a priority of his work.

That focus can appear jarring to some prelates in a church that invests in multi-million dollar real estate, possesses priceless artworks and conducts its liturgical services often amid splendour, such as in the magnificence of St. Peter's, other basilicas and cathedrals.

Francis' emphasis on mercy and charity has also raised the hackles of a small, but noisy faction among the more conservative ranks of bishops and cardinals, who would rather the head of the Catholic church concentrate more on dogma than on persons.

Some 150 tables were set up in a Vatican hall where the Pope usually holds weekly indoor audiences with the public.

Another 1,500 needy will be treated to a separate lunch elsewhere in Rome, while parishes throughout Italy were similarly setting out lunch for those unable to afford their own.

Australian Associated Press